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authorIngela Anderton Andin <[email protected]>2017-11-07 18:34:34 +0100
committerIngela Anderton Andin <[email protected]>2017-11-09 16:39:46 +0100
commit3b4386dd19b7e669f557c95ace8d7ba228291927 (patch)
tree52c3eea1f9c4a90864172cebfadc446343d2bf3b
parent2cc46961352aded5c84ecb9bcb32581461dbc047 (diff)
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ssl: Countermeasurements for Bleichenbacher attack
-rw-r--r--lib/ssl/src/dtls_connection.erl1
-rw-r--r--lib/ssl/src/ssl_connection.erl21
-rw-r--r--lib/ssl/src/ssl_connection.hrl1
-rw-r--r--lib/ssl/src/tls_connection.erl1
4 files changed, 22 insertions, 2 deletions
diff --git a/lib/ssl/src/dtls_connection.erl b/lib/ssl/src/dtls_connection.erl
index 745db788e7..130a8bb1c5 100644
--- a/lib/ssl/src/dtls_connection.erl
+++ b/lib/ssl/src/dtls_connection.erl
@@ -575,6 +575,7 @@ handle_client_hello(#client_hello{client_version = ClientVersion} = Hello,
State = prepare_flight(State0#state{connection_states = ConnectionStates,
negotiated_version = Version,
+ client_hello_version = ClientVersion,
hashsign_algorithm = HashSign,
session = Session,
negotiated_protocol = Protocol}),
diff --git a/lib/ssl/src/ssl_connection.erl b/lib/ssl/src/ssl_connection.erl
index ad220ae9de..0e51106bfb 100644
--- a/lib/ssl/src/ssl_connection.erl
+++ b/lib/ssl/src/ssl_connection.erl
@@ -1367,8 +1367,25 @@ server_certify_and_key_exchange(State0, Connection) ->
request_client_cert(State2, Connection).
certify_client_key_exchange(#encrypted_premaster_secret{premaster_secret= EncPMS},
- #state{private_key = Key} = State, Connection) ->
- PremasterSecret = ssl_handshake:premaster_secret(EncPMS, Key),
+ #state{private_key = Key, client_hello_version = {Major, Minor} = Version} = State, Connection) ->
+
+ %% Countermeasure for Bleichenbacher attack always provide some kind of premaster secret
+ %% and fail handshake later.RFC 5246 section 7.4.7.1.
+ PremasterSecret =
+ try ssl_handshake:premaster_secret(EncPMS, Key) of
+ Secret when erlang:byte_size(Secret) == ?NUM_OF_PREMASTERSECRET_BYTES ->
+ case Secret of
+ <<?BYTE(Major), ?BYTE(Minor), _/binary>> -> %% Correct
+ Secret;
+ <<?BYTE(_), ?BYTE(_), Rest/binary>> -> %% Version mismatch
+ <<?BYTE(Major), ?BYTE(Minor), Rest/binary>>
+ end;
+ _ -> %% erlang:byte_size(Secret) =/= ?NUM_OF_PREMASTERSECRET_BYTES
+ make_premaster_secret(Version, rsa)
+ catch
+ #alert{description = ?DECRYPT_ERROR} ->
+ make_premaster_secret(Version, rsa)
+ end,
calculate_master_secret(PremasterSecret, State, Connection, certify, cipher);
certify_client_key_exchange(#client_diffie_hellman_public{dh_public = ClientPublicDhKey},
diff --git a/lib/ssl/src/ssl_connection.hrl b/lib/ssl/src/ssl_connection.hrl
index b597c059af..016cc4b525 100644
--- a/lib/ssl/src/ssl_connection.hrl
+++ b/lib/ssl/src/ssl_connection.hrl
@@ -57,6 +57,7 @@
session_cache_cb :: atom(),
crl_db :: term(),
negotiated_version :: ssl_record:ssl_version() | 'undefined',
+ client_hello_version :: ssl_record:ssl_version() | 'undefined',
client_certificate_requested = false :: boolean(),
key_algorithm :: ssl_cipher:key_algo(),
hashsign_algorithm = {undefined, undefined},
diff --git a/lib/ssl/src/tls_connection.erl b/lib/ssl/src/tls_connection.erl
index 831bbefc59..b18c69c740 100644
--- a/lib/ssl/src/tls_connection.erl
+++ b/lib/ssl/src/tls_connection.erl
@@ -280,6 +280,7 @@ hello(internal, #client_hello{client_version = ClientVersion} = Hello,
gen_handshake(ssl_connection, hello, internal, {common_client_hello, Type, ServerHelloExt},
State#state{connection_states = ConnectionStates,
negotiated_version = Version,
+ client_hello_version = ClientVersion,
hashsign_algorithm = HashSign,
session = Session,
negotiated_protocol = Protocol})